Orateur
Victoria Wagner
(Max-Planck-Institut fuer Kernphysik)
Description
The GERDA experiment searches for neutrinoless double beta ($0\nu\beta\beta$) decay of $^{76}$Ge using high purity germanium (HPGe) detectors operated in liquid argon (LAr).
The aim is to explore half-lives of the order of $10^{26}$\,yr.
Therefore, GERDA relies on improved active background reduction techniques such as pulse shape discrimination (PSD) in which the time structure of the germanium signals is analyzed to discriminate signal- from background-like events.
Phase II of the experiment includes a major upgrade: for further background rejection, the LAr cryostat is instrumented to detect argon scintillation light (LAr veto).
In a first data release, a new limit on the half-life of $0\nu\beta\beta$ decay of $^{76}$Ge is set to
T$_{1/2}^{0\nu}\,>\,5.3\,\cdot\,10^{25}$ yr at 90 % C.L., with a median sensitivity of $T_{1/2}^{0\nu}\,>\,4.0\,\cdot\,10^{25}$ yr at 90 % C.L.
GERDA Phase II proved to be a high resolution experiment and background-free: together, PSD and LAr veto achieve a BI of the order of $10^{−3}$ $\frac{counts}{keV \cdot kg \cdot yr}$. With this unprecedented BI, less than one background event is expected until an exposure of 100 kg$\cdot$yr. The talk presents the current status of the experiment.
Author
Victoria Wagner
(Max-Planck-Institut fuer Kernphysik)
